Among various kinds of illumination devices provided with LED elements, there is known an illumination device that places emphasis the high efficiency. The illumination device placing emphasis on the high efficiency is superior in light emission efficiency but inferior in color rendering property. It is also likely that the visual perception of the color of an object or a human skin irradiated by the light of the illumination device may become unfaithful.
In light of this, Japanese Patent Application Publication No. 2010-176992 discloses an illumination device placing emphasis on the high color rendering property. This illumination device takes into account, e.g., an average color rendering index Ra and a special color rendering index No. 15 (R15), in order to assure faithful visual perception of the color of an object or a human skin.
In the illumination device referred to above, the visual perception of a human skin color or the like is made faithful (the color rendering property is kept high) by increasing an average color rendering index Ra and a special color rendering index. No. 15 (R15). In recent years, a demand exists for an illumination device capable of not only having a skin color look faithful but also having the skin color look preferable.